In general, there is known a hydraulic control device used in a working vehicle such as a wheel loader or the like, which is equipped with a dynamic damper to reduce vibrations at traveling for improving ride comfort (Patent Documents 1, 2, 3 and 4).
In the conventional art of this type, a bottom-side oil chamber in a boom cylinder provided in the working mechanism of the wheel loader is connected via communication lines such as hoses, pipes or the like to an accumulator. At the traveling of the wheel loader, pressure pulsations generated due to vibrations of a bucket as a weight load are absorbed by the accumulator for a vibration reduction in a vehicle and an improvement of the ride comfort thereof.